PRIOR CONCURRENT THERAPY: Biologic therapy: See Disease Characteristics At least 3 months since prior immunotherapy for respiratory syncytial virus (RSV) including RSV hyperimmune globulin or other RSV monoclonal antibodies Concurrent IV immunoglobulin allowed No prior experimental RSV vaccine No concurrent RSV hyperimmune globulin No other concurrent RSV-specific monoclonal antibodies Chemotherapy: Not specified Endocrine therapy: See Disease Characteristics Radiotherapy: Not specified Surgery: Not specified Other: At least 4 weeks since prior investigational products for respiratory viral diseases At least 3 months since prior anti-viral drugs with specific anti-RSV activity Prior aerosolized ribavirin allowed No other concurrent anti-viral drugs with specific anti-RSV activity Concurrent ganciclovir or foscarnet allowed Ventilator support allowed